Unveiling of efficiency limit to fabricate high-performance PbSe quantum dot solar cells

Lead selenide quantum dots (PbSe QDs), as promising active absorbers, have received considerable attention in solar cells. However, the performance of PbSe QD-based solar cells (PbSe QDSCs) still lags behind that of c-Si and perovskite solar cells mainly due to non-radiative and resistive losses. To investigate the limitation of PbSe QDSCs, we established a theoretical model based on the performance of the state-of-the-art PbSe QDSCs through diffusion-drift theory and systematically discussed the optional strategies for optimizing the efficiency of PbSe QDSCs. The optimizations were initially carried out in term of absorber layer thickness, defect densities in absorber layer and interface defect layer (IDL), thus yielding a power conversion efficiency (PCE) of 15.25% with open-circuit voltage (Voc) of 0.64 V and fill factor (FF) of 74.49% in PbSe QDSCs. After the modifications of the doping concentrations of charge transport layers and the band alignment in solar device, the PbSe QDSCs can achieve over 30% efficiency with a ∼80% and 32 % improvement in Voc and FF, respectively. Our findings gained here provide effective experimental guidelines and pave the way for PbSe QDSCs to approach their theoretical efficiency limit.